It's "Containment"!!! There I said it. So what do I mean you say? I compare it to a fine perfume inside a beautiful bottle, you don't want a bottle which cap opens wide because it lets out all the scent and if you leave it like that it loses a lot of it, not to mention that the scent is too strong, unlike when you just spritz it lightly on your body to enhance and please your senses.
Life presents challenges every single day, and the more we develop as a species the greater the challenges. Just on a regular day he/she comes home and is tired, either sat at an office surrounded by co-workers of all types and personalities, or his/her work is physical or mental, might be all day on the streets fighting traffic or helping people, encountering tons of challenges and all he/she wants to do is go home to his/her refuge and be with you. Maybe he/she wants to share his/her day maybe not. So he/she gets home and you've been dealing with your own day to day challenges, sometimes less sometimes more, but it's life and stuff happens all the time.
I don't believe there is any "Free Will", yes we choose who we marry but can we choose what he/she will do on any certain day? we can decide to have kids, but can we choose what they make of themselves? we can choose our careers, jobs and our friends, but that's about where the "Free Will" begins and ends because outside of our choices there are all these circumstances that are totally out of our control that can make our choices either succeed or fail, so for me what works is having someone to LOVE unconditionally who wants to be loved and LOVES me in return the same way, so much so, that is willing to help me contain my 'Monster Within'.
Make sure the partner you chose to share this life adventure with is helping you contain that monster instead of being the one who opens the cap and lets it escape, look inside and see if you're not the one who awakens theirs, be more selfless and help them become a better version of themselves, be brave, caring and do something about it. It is worth every effort you make.
Are you containing each other with LOVE!?